Method of making heat sink

ABSTRACT

A method of making a heat sink ( 10 ) includes the following steps: providing a base ( 11 ) and a plurality of individual fins ( 13 ), and welding the fins successively to the base by ultrasonic welding method.

BACKGROUND

1. Technical Field

The present invention generally relates to heat sinks, and more particularly to a method of making a heat sink used for dissipating heat from heat-generating components.

2. Description of Related Art

It is well known that heat is produced by electronic components such as integrated circuit chips during their normal operations. If the heat is not timely removed, these electronic components may overheat. Therefore, heat sinks are often used to cool these electronic components.

Presently, a typical heat sink includes a base and a fin assembly attached to the base. The base thermally contacts with a heat generating electronic component. The fin assembly includes a plurality of fins joined together. The fin assembly is welded to the base via tin soldering method. However, solder and flux are required during soldering of the heat sink. Specially, when the base and the fin assembly are respectively made of different materials, such as copper and aluminum, an additional process for coating a nickel layer on welding surfaces of the base and the fin assembly is needed. Thus, the cost of the heat sink is increased and the process of making the heat sink is complicated. In addition, during the soldering process, tiny air bubbles will be formed between the fin assembly and the base, thereby increasing a heat resistance between the base and the fin assembly, which further decreases the heat dissipating efficiency of the heat sink.

What is needed, therefore, is a new method of making a heat sink which can overcome the shortcomings of the prior art.

SUMMARY

The present invention relates to a method of making a heat sink. According to a preferred embodiment of the present invention, the method of making the heat sink includes the following steps: providing a base and a plurality of individual fins, and welding the fins successively to the base by ultrasonic welding method.

Other advantages and novel features of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the present method can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present method. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.

FIG. 1 is an isometric view showing fins of a heat sink to be joined to a base of the heat sink by an ultrasonic welding process in accordance with a first embodiment of the present invention.

FIG. 2 is an assembled, isometric view of the heat sink of FIG. 1.

FIG. 3 is an isometric view showing fins of a heat sink to be jointed to a base of the heat sink by an ultrasonic welding process of a heat sink in accordance with a second embodiment of the present invention.

FIG. 4 is an assembled, isometric view of the heat sink of FIG. 3.

DETAILED DESCRIPTION

Referring to FIG. 1, an ultrasonic welding process of a heat sink 10 in accordance with a first embodiment of the present invention is shown. Firstly, a base 11 and a plurality of individual fins 13 are provided.

The base 11 has a rectangular shape. The base 11 is made of copper, which has good thermal conductivity. The base 11 has a contacting surface 111 at a top thereof.

The fins 13 are made of aluminum, which has good thermal conductivity. Aluminum has a lower thermal conductivity than copper. Each fin 13 has a plate shape, and has a thickness in a range of 0.3˜0.4 mm. Each fin 13 includes a rectangular main body 133, and a flange 134 extending vertically and outwardly from a bottom side of the main body 133.

During assembly of the heat sink 10, the fins 13 are successively welded to the base 11 by ultrasonic welding method. Specifically, the flange 134 of each fin 13 is welded on the contacting surface 111 of the base 11 by the ultrasonic welding method. When one of the fins 13 is welded on the contacting surface 111 of the base 11, a welding area 136 is defined at a front side of the welded one of the fins 13 for receiving another one of the fins 13 to be soldered to the base 11. The ultrasonic welding can seamlessly join two workpieces together when the workpieces are under high-frequency ultrasonic acoustic vibrations and pressure.

The ultrasonic welding method has many advantages, such as environment friendly, cleaning, energy and time saving and so on. The ultrasonic welding method not only fits for joining different materials, but also has a lower requirement with respect to the quality of the surfaces to be welded together. Oxidated and electroplated surfaces also fit for the ultrasonic welding method. Although the base 11 and the fins 13 of the heat sink 10 are respectively made of copper and aluminum, the ultrasonic welding method can easily weld the base 11 and the fins 13 together. In addition, the base 11 and the fins 13 are seamlessly welded together by the ultrasonic welding method, thereby decreasing the heat resistance between the base 11 and the fins 13. Thus, heat dissipating efficiency of the heat sink 10 is accordingly improved. Furthermore, solder and flux are not required during the ultrasonic welding method, whereby the cost of the heat sink 10 is decreased and the process of making the heat sink 10 is simplified.

In the ultrasonic welding method, a required power is increased dramatically along with an increase of the thickness of the workpiece being welded. However, in the heat sink 10, each fin 13 has a small thickness in the range of 0.3˜0.4 mm; thus, the required power for welding each fin 13 is in an acceptable range, thereby decreasing unnecessary energy consumption. In addition, a larger welding head is generally required in the ultrasonic welding. However, in the heat sink 10, the flanges 134 of the fins 13 are successively welded on the contacting surface 111 of the base 11 by the ultrasonic welding method. Thus, the welding head can be small. The welding area 136 defined at the front side of the fin 13 to be welded can provide an adequate enough space for the welding head to press the flange 134 of the fin 13 to be welded. Thus, the welding head can conveniently and evenly apply the pressure on the flange 134 of each fin 13 to be welded, which helps the fins 13 to have an intimate connection with the base 11.

Referring to FIG. 2, the heat sink 10 made by the ultrasonic welding method is shown. The fins 13 of the heat sink 10 are stacked together and parallel to each other. A bottom surface of the base 11 of the heat sink 10 thermally contacts with a heat generating component (not shown) to absorb heat therefrom, and then transfers the heat towards the fins 13.

Referring to FIG. 3, an ultrasonic welding process of a heat sink 20 in accordance with a second embodiment of the present invention is shown. Firstly, a base 21 and a plurality of individual fins 23 are provided.

The base 21 has a cylindrical shape. The base 21 is made of copper, which has good thermal conductivity. The base 21 has a circular contacting surface 211 at a circumference thereof.

The fins 23 are made of aluminum, which has good thermal conductivity. Each fin 23 has a plate shape, and has a thickness in a range of 0.3˜0.4 mm. Each fin 23 includes a main body 233, and a flange 234 extending vertically and outwardly from an inner side of the main body 233. The main body 233 of each fin 23 includes a lower part 237, a middle part 238 and an upper part 239. A length from an inner side towards an outer side of each of the lower part 237, the middle part 238 and the upper part 239 is successively increased, thereby forming two sidesteps at an outer side of the main body 233.

During assembly of the heat sink 20, the fins 23 are successively welded to the base 21 by ultrasonic welding method. Specially, the flange 234 of each fin 23 is welded on the contacting surface 211 of the base 21 by the ultrasonic welding method. When one of the fins 23 is welded on the contacting surface 211 of the base 21, a welding area 236 is defined at a front side of the welded fin 23.

Referring to FIG. 4, the heat sink 20 made by the ultrasonic welding method is shown. The fins 23 of the heat sink 20 are radially welded to the base 21. A bottom surface of the base 21 of the heat sink 20 thermally contacts with a heat generating component (not shown) to absorb heat therefrom, and then transfers the heat towards the fins 23.

It is believed that the present invention and its advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention. 

1. A method of making a heat sink, comprising: providing a base and a plurality of individual fins; and welding the fins successively to the base by ultrasonic welding method.
 2. The method of making a heat sink of claim 1, wherein the base is made of copper, and the fins are made of aluminum.
 3. The method of making a heat sink of claim 1, wherein the base has a rectangular shape, and the fins are stacked together and parallel to each other.
 4. The method of making a heat sink of claim 1, wherein the base has a cylindrical shape, and the fins are radially welded to the base.
 5. The method of making a heat sink of claim 4, wherein each fin includes a lower part, a middle part and an upper part, and a length from an inner side towards an outer side of each of the lower part, the middle part and the upper part is successively increased.
 6. The method of making a heat sink of claim 1, wherein each fin includes a main body and a flange extending outwardly from the main body, the flange of each fin being welded to the base by the ultrasonic welding method.
 7. The method of making a heat sink of claim 6, wherein each fin has a thickness in a range of 0.3˜0.4 mm.
 8. The method of making a heat sink of claim 1, wherein each fin has a thickness in a range of 0.3˜0.4 mm. 